Filed of the Invention
The present invention relates to a semiconductor device and its manufacturing method, and in particular to a technology that is effective when it is applied to a semiconductor device in which an aluminum pad electrode and a lead frame are connected with bonding wire by a ball bonding technology.
Description of the Related Art
Wire bonding that connects pad electrodes of a semiconductor chip in which an integrated circuit is built and electrodes of a printed circuit board or a semiconductor package using wire such as of gold (Au) and of copper (Cu) has been widely adopted as a mounting technology that features a relatively low cost and a high degree of freedom of wiring.
Meanwhile, with high integration of the semiconductor integrated circuit, pitch narrowing and film thinning of the pad electrode of the semiconductor chip have progressed, improvement of reliability of the wire bonding in miniaturization of the semiconductor integrated circuit has become an issue, because problems of exfoliation of the pad electrode from an interlayer insulation film and a damage of the interlayer insulation film under the pad electrode become remarkable.
There is a technology as described in Patent Document 1 as a background art of this technical field. Patent Document 1 discloses a “semiconductor device that has a pad electrode whose adhesion with an insulation film does not fall by configuring a pad electrode to be a two-layer structure of a first pad electrode and a second electrode and by connecting the first pad electrode and the second electrode with a metal layer (via).”
[Patent Document]
[Patent document 1] Japanese Patent No. 2964999
The above-mentioned Patent Document 1 is such that a pad electrode is formed with a two-layer structure, and this is an effective technology to exfoliation of the pad electrode from an interlayer insulation film. Meanwhile, when performing wire bonding to a semiconductor chip, since an ultrasonic wave is applied to a bonding ball formed in a tip of bonding wire with a fixed load added by a capillary, a large stress is applied to a lower part of the capillary.
With the pad electrode of the two-layer structure in which metal layers (vias) are arranged in a matrix form all over the pad electrode like Patent Document 1, the interlayer insulation film in which a metal layer (vias) located immediately under a location where the bonding ball contacts the capillary end is formed has a problem that cracks easily occur by this stress.